I came to soil from the stars. In my first book, The End of Night: Searching for Natural Darkness in an Age of Artificial Light, I did my best to call attention to the value of darkness and the many costs from light pollution. Most people in modern cities and suburbs—especially the younger among us—have no idea what a real starry sky looks like, and no idea of what they’re missing. The fact that life on earth evolved with bright days and dark nights, and needs both light and darkness for optimal health, is something most of us never think about. When I began to imagine the next book I would write, I quickly realized the same is true of soil.

It’s hard to believe that so few people understand how important soil is for our survival. Hard to believe, perhaps, until you hear the estimate that we in the west spend on average 90-95% of our time inside, cut off from the natural world. My new book, The Ground Beneath Us: From the Oldest Cities to the Last Wilderness, What Dirt Tells Us about Who We Are, began when I heard this stunning number. It wasn’t long before I realize that when we do walk outside, we mostly walk on pavement or asphalt. We have gone from being intimately in touch with the natural ground at our feet to being almost completely separated from it. From there, I began to see how this literal separation was symbolic of our separation from the different grounds that give us our food, our water, our energy, and even our spirit. I decided to explore the many costs of this separation, and the value of knowing the life at our feet.

I certainly could have written an entire book about the wonderful subject of soil. But I decided to place our relationship with soil within the larger subject of our relationship with the ground. I was fascinated by the notion that the oldest spiritual traditions and the newest sciences tell us the same thing about the ground—that it’s alive, and that we would be wise to treat it carefully. I was intrigued as well by the different kinds of “grounds” that give meaning to our lives, such as battlegrounds and burial grounds, hallowed ground and ground we deem sacred. I was—and continue to be—especially interested in the question, Why do we live so separated from and ignorant of that which sustains us?

From the paved ground of New York, London, and Mexico City, to the grounds that would inspire me to ponder the sacred—the Nazi death camp at Treblinka in Poland, the wild tundra of Alaska’s southwest—I went looking for answers. Between these bookends I placed the chapters in which I sought to share the amazing, mysterious, known-more-than-ever and yet still-barely-known world of soil. The similarities to the stars came back to me here. The numbers so large they bend our brains as we try to comprehend. The galaxies upon galaxies beyond anything we now know. And especially, the way that once you know what’s out there, you never look at the sky—or, in this case the ground—the same way again.

Everywhere I go now I find myself looking at the ground with wonder. This is the feeling that stays with me after writing this new book. Wonder that everything growing—even us, if we pause long enough to realize—is anchored in soil, dependent on its life for our life. If I had one wish for the new book, it would be that it help more people to realize this, and bring to soil the attention and respect it deserves. It would be that we would walk outside, look down, and know what we have been missing.